The present invention relates to water-soluble compositions of bioactive lipophilic compounds, to compounds useful for the preparation of such compositions, to methods of preparing such compounds and compositions, and to the use of such compositions as therapeutics and cosmetics.
Many bioactive compounds are highly lipophilic (hydrophobic), meaning that they are soluble in lipids (oils) and some organic solvents, while being substantially insoluble or only sparsely soluble in water. The lack of solubility of a bioactive compound in aqueous media is an important factor limiting its therapeutic applications, making difficult an efficient administration of the compound to a patient. When administered in the form of an oil solution or some kind of water and/or oil suspension or emulsion, lipophilic compounds usually show a poor bioavailability, meaning a low concentration and a long build-up time of the compound in the systemic circulation. This lack of bioavailability is usually independent of the administration route (topical, oral, or parenteral).
Various approaches to overcoming this limitation are known in the prior art. One known approach consists of dissolving a lipophilic compound in a water-miscible organic solvent, such as ethanol or propylene glycol. When such a solution is admixed with blood or gastrointestinal fluids, however, the lipophilic compound usually precipitates as a solid or liquid emulsion, with a resulting low bioavailability. Furthermore, for many lipophilic compounds no organic, water-miscible solvents exist. Another approach consists of incorporating lipophilic compounds into various compositions, frequently inhomogeneous, multiphase emulsions, containing oils and solvents in combination with surfactants. These compositions may improve the bioavailability of the compound without significantly increasing its solubility in aqueous media, but are normally suitable only for a particular administration form, usually for topical applications. Such compositions, which may also induce a protective immune response in mammals, are of little value for therapeutic uses where administration of the compound by ingestion or injection is necessary and where an aqueous solution or a water-soluble solid composition is frequently the only acceptable administration form.
Several approaches to preparing homogenous aqueous solutions of lipophilic bioactive compounds are also known in the prior art. One method consists of preparing a derivative or an analog of a lipophilic compound having a better solubility in water than the original compound. In the simplest case, this derivative may be a water-soluble salt of the compound, which salt usually retains the original biological activity, but this approach is applicable only to compounds having acidic or basic properties. If more substantial modifications are introduced into the original compound to improve its solubility, a decrease or even a complete loss of the original bioactivity of the compound is frequently observed.
Another method of solubilization consists of preparing a water-soluble derivative capable of liberating the original bioactive compound under physiological conditions. Such derivatives, also known as pro-drugs, usually improve bioavailability of the compound and may also ensure a targeted delivery of the compound or its sustained release over a period of time. However, this approach usually relies on the presence of certain functional groups in the original compound, so it is not universally applicable. In addition, synthetic methods of improving solubility of a compound by chemical modifications are relatively complicated and expensive.
Still another approach to solubilization of bioactive lipophilic compounds relies on formation of water-soluble complexes. An example are complexes with amphipathic compounds containing moieties of two opposing solubility tendencies (lipophilic and hydrophilic). Such compounds are often soluble both in organic solvents and in water, so that the solubilization is usually achieved by dissolving a bioactive lipophilic compound and an amphipathic compound in a suitable water-miscible organic solvent and diluting the solution with water. In some cases the organic solvent is partially or entirely removed from the original or water-diluted solution by evaporation or lyophilization and the concentrate reconstituted with a suitable aqueous medium, without precipitation of the water-insoluble lipophilic compound. When the auxiliary organic solvent cannot be completely removed from the composition, this solvent must be pharmaceutically acceptable, which limits the choice of applicable solvents.
Bioactive lipophilic compounds in need of solubilization belong to various therapeutic categories, such as vitamins (e.g., Vitamin E), antibiotics, in particular macrolide polyene antibiotics (amphotericin-B, nystatin, candicidin), free radicals scavengers (e.g., tocopherols, ubiquinones), immunosuppressants (e.g., cyclosporine), etc. Various approaches to achieve the solubility and improve the bioavailability of these and other lipophilic compounds are known in the prior art, including formation of water-soluble complexes.
U.S. Pat. No. 5,686,110 discloses water-soluble complexes of water-insoluble compounds, including amphotericin-B and cyclosporine, with a polyalkylene oxide polymers end-capped with an alkyl or olefinic group, which polymers are soluble both in water and in organic solvents. The water-soluble complexes, which are formed only in the presence of an auxiliary organic solvent, are lyophilized and reconstituted with a buffer solution. The reconstituted aqueous solutions show only a limited stability, depending mostly on the pH of the solution. Furthermore, the use of methoxypolyethylene glycol polymers of relatively high molecular weight (2,000 to 5,000) as preferred solubilizing agents increases the amount by weight of polymer necessary for solubilization of the bioactive compound.
U.S. Pat. No. 5,798,333 discloses a homogenous, water-soluble composition (concentrate) of cyclosporine, which can be diluted with an aqueous solution without precipitation of cyclosporine. The concentrate comprises cyclosporine and tocophersolan (polyoxyethanyl-xcex1-tocopheryl succinate, TPGS) dissolved in a hydrophilic organic solvent, such as propylene glycol. Solvent-free compositions are not disclosed, as they would likely be unstable or inhomogeneous.
WO 96/17626 discloses water-soluble compositions of ubiquinones comprising polyoxyethanyl-cholesteryl sebacate (PCS) as a solubilizing agent. A ubiquinone, in particular Coenzyme Q10, is solubilized by dissolving both Coenzyme Q10 and PCS in tetrahydrofuran at an approximate molar ratio of 1:3 and diluting this solution with water. The solution is then evaporated to dryness under reduced pressure and reconstituted with a suitable buffer solution.
Coenzyme Q10 (CoQ10) is a natural compound whose therapeutic potential has been recently recognized for a number of disorders, including congestive heart failure, muscular distrophy, periodontal disease, correction of drug-induced deficiencies, and immune restoration (AIDS, allergies), to name a few. Coenzyme Q10 is also of great interest to cosmetic industry, since it can be included into cosmetic preparations as agent slowing down natural skin ageing processes. The biological activity of Coenzyme Q10 is believed to be linked to its ability to act as an antioxidant and free radical scavenger protecting integrity of cell membranes and to offset the inability of diseased cells to manufacture sufficient energy for cellular repair, by stimulating mitochondrial respiration and production of ATP. For effectiveness in both clinical and cosmetic applications, preparations of Coenzyme Q10 with high bioavailability and solubility in aqueous media are usually required.
Even though various methods of improving solubility of lipophilic compounds, such as Coenzyme Q10, in aqueous media are known in the prior art, they are not equal in terms of simplicity, scope of applicability, stability of the prepared formulations, etc. The present invention provides a new method of solubilization of lipophilic compounds, which is free of many prior art drawbacks and limitations.
According to one aspect, the present invention provides a water-soluble composition comprising a lipophilic compound and a solubilizing agent of the general formula:
{Xxe2x80x94OOCxe2x80x94[(CH2)nxe2x80x94COO]m}pxe2x80x94Yxe2x80x83xe2x80x83(I) 
wherein:
X is a residue of a hydrophobic moiety,
Y is a residue of a hydrophilic moiety,
p is 1 or 2,
m is 0 or 1, and
n is an integer greater than or equal to 0.
The lipophilic compound is preferably selected from the group consisting of ubiquinones, ubiquinols, vitamins, provitamins, polyene macrolide antibiotics, and mixtures thereof. The hydrophobic moiety is preferably a sterol or a tocopherol and the hydrophilic moiety is preferably a polyalkylene glycol. In preferred embodiments, the sterol is cholesterol or sitosterol, the tocopherol is xcex1-(+)-tocopherol, the polyalkylene glycol is a polyethylene glycol or its methyl monoether having an average molecular weight between 400 and 1000, p is equal to 1 or 2, m is equal to 0 or 1 and n is an integer between 2 and 18.
According to another aspect of the invention, a water-soluble composition comprising a bioactive lipophilic compound and a solubilizing agent of the general formula
{Xxe2x80x94OOCxe2x80x94[(CH2)nxe2x80x94COO]m}pxe2x80x94Y 
wherein:
p is 1 or 2,
m is 0 or 1, and
n is an integer in the range Oxe2x89xa6nxe2x89xa618
X is a residue of a hydrophobic moiety selected from the group consisting of cholesterol, 7-dehydrocholesterol, campesterol, sitosterol, ergosterol, stigmasterol, and xcex1-, xcex2-, xcex3-, and xcex94-tocopherols and derivatives thereof, Y is a residue of a hydrophilic moiety, selected from the group consisting of polyalcohols, polyethers, polyanions, polycations, polyphosphoric acids, polyamines, polysaccharides, polyhydroxy compounds, polylysines and derivatives thereof, provided that:
when p and m are equal to 1 and the hydrophobic moiety is (+)-xcex1-tocopherol, n is not equal to 2.
According to another aspect, the invention provides a method of preparation and purification of a water-soluble composition comprising a solubilizing agent of the general formula (I), in the presence or in the absence of an auxiliary organic solvent. The solubilization is achieved by dissolving a water-insoluble lipophilic compound and a solubilizing agent in a water-miscible organic solvent, diluting the solution with water, and removing the organic solvent and optionally a part of water under reduced pressure. Alternatively, a lipophilic compound and solubilizing agent can be admixed directly in a predetermined molar ratio and heated to a temperature higher than the their respective melting points, to form a water-soluble composition in the form of a clear melt, which can be then diluted with an aqueous solution to a desired concentration. The water-soluble composition may be additionally purified by dissolving it in a small amount of water, heating the solution until the composition separates as a clear liquid phase, and removing the separated composition from the solution while keeping the temperature of the solution substantially unchanged.
According to still another aspect, the invention provides pharmaceutical or cosmetic formulations comprising a water-soluble composition of a lipophilic compound and a solubilizing agent of formula (I).
According to yet another aspect, the invention provides novel solubilizing agents of formula (I) and methods of their preparation and purification.
According to a further embodiment of the invention, a method is provided for the treatment of a fungal infection in humans or warm-blooded animals in need of such treatment, comprising administering to such human or warm-blooded animal, a therapeutically effective amount of a water-soluble composition, comprising a solubilizing agent selected from the group consisting of polyoxyethanyl-sitosterol sebacate, polyoxyethanyl-cholesteryl sebacate and polyoxyethanyl-xcex1-tocopheryl sebacate, and a macrolide polyene antibiotic, formulated in a weight ratio of solubilizing agent to antibiotic of 2:1 to 4:1, in conjunction with a pharmaceutically effective carrier or excipient.
According to a yet further embodiment of the invention, a water-soluble composition is provided, comprising, a solubilizing agent selected from the group consisting of polyoxyethanyl-sitosterol sebacate, polyoxyethanyl-cholesteryl sebacate and polyoxyethanyl-xcex1-tocopheryl sebacate, and a macrolide polyene antibiotic, formulated in a weight ratio of solubilizing agent to antibiotic of 2:1 to 4:1.
According to a still further embodiment of the invention, a method is provided for preparing a water-soluble composition, comprising the steps of,
(a) dissolving the antibiotic and the solubilizing agent in a water-miscible organic solvent, in a weight ratio of solubilizing agent to antibiotic of 2:1 to 4:1,
(b) removing from the solution the organic solvent to achieve a desired concentration of the water soluble composition,
(c) dissolving the composition in water, and
(d) drying.
According to a yet further embodiment of the invention, a method is provided for delivery of xcex1-tocopherol to humans or warm-blooded animals in need thereof, comprising administering to such human or warm-blooded animal, an effective amount of a water-soluble form of vitamin E.
PTS is a water-soluble form of vitamin E. We have found that in the body of an animal, water-soluble forms of vitamin E, such as PTS, get hydrolysed and are systemically converted back to xcex1-tocopherol, an active non-toxic form of vitamin E. Accordingly, PTS can itself be administered to an animal in need thereof, as a means for delivery of active non-toxic vitamin E.
According to a yet further embodiment of the invention, a water-soluble composition is provided, comprising a solubilizing agent selected from the group consisting of polyoxyethanyl-sitosterol sebacate, polyoxyethanyl-cholesteryl sebacate and polyoxyethanyl-xcex1-tocopheryl sebacate, and a compound having a high content of polyunsaturated fatty acids and derivatives thereof. Derivatives include mono-, di- and tri-glycerides and their aliphatic esters. Examples of such compounds include fish oils, plant oils and other plant extracts. Further examples of such compounds can be found in the literature in B. Fitch Haumann: Alternate Sources for n-fatty acids in: Informxe2x80x94International news on fats, oils and related materials (1998) vol. 19 no. 12, p. 1108, and in G. Fernandes et al. Role of omega-3 fatty acids in health and disease. In: Nutrition Research (1993) vol. 13, 19-45, the disclosures of which are incorporated herein by reference.
According to a still further embodiment of the invention, a water-soluble composition is provided, comprising a solubilizing agent selected from the group consisting of polyoxyethanyl-sitosterol sebacate, polyoxyethanyl-cholesteryl sebacate and polyoxyethanyl-xcex1-tocopheryl sebacate, and a bioactive lipophilic compound selected from the group consisting of a terpene and a terpenoid.
We have now solubilized in water xcex1-tocopheryl acetate, a synthetic form of vitamin E, using various solublizing agents including PTS-600 and PTS-400.
The ratio of solubilizing agent to xcex1-tocopheryl-acetate was in the range of 2:1 to 5.5:1 w/w. Water-soluble compositions were obtained using either the awaiting solvent eg THF method, or the direct admixing method described above.
Tocotrienols are water-insoluble tocopherol derivatives, useful as antioxidants. We have now made a pegylated form of a tocotrienol polyoxyethanyl tocotrienyl sebacate (PTrienS-600), which is useful as a solubilizing agent. The method is described below. In particular, see examples 31 and 32. It will be appreciated that this invention is also applicable to other tocotrienols such as those described in www.eastman.com/online publications, Nutriene tocotrienols. Publication v-24,(1998), the disclosure of which is incorporated herein by reference. We have also dissolved the tocotrienols in water, using a solubilizing agent eg. PTS-600 or a pegylated tocotrienols polyoxycthanyltocotrienyl sebacate eg (PtrieneS-600.) (see example 32). The ratio of solubilizing agent to tocotreinols is about 5.5:1 w/w. The water-soluble compositions are obtained using either the auxiliary solvent method, or the direct admixing methods described above.
We have also shown that CoQ10 can be water solublized using either PTS-400, or pegylated derivatives of tocotrienols, such as polyoxyethanyltocotrienyl sebacate (PTriensS-600) as solubilizing agent. The ratio of solubilizing agent to CoQ10 was in the range 2.5:1 to 3.5:1. The direct admixing method described above was used. See example 33.